Study of topologies and architectures of DC-AC photovoltaic converters connected to the grid

Abstract

This thesis proposes a new control structure for two multilevel three-phase inveter topologies for photovoltaic (PV) systems connected to the grid. This control scheme include the use of the space vector pulse wide modulation (SVPWN) technique to control the Diode Clamped Inverter (DCI) and cascade inverter topologies and the integration of a particle swarm optimization (PSO) technique to operate the PV system at the Maximum Power Point (MPP). An FPGAimplementation of PSO based MPPT is proposed to overcome the problem of MPP tracking under partial shading condition. This MPPT technique is validates under various PV array configuration in order to evaluate the behavior of each PV configuration under non-uniform irradiation. AnSVPWM control strategy is used in order to generate gate control signals for the inverter and implemented for both DCI and cascade inverter topologies. Then, a comparative study of photovoltaic systems with these inverter topologies is carried out under MATLAB/Simulink environment and evaluated on the basis of MPPT, harmonic distotion, cost, advantages and disadvantages. In order to test the practical implementation of the proposed control structure, FPGA/Simulink-based Hardware in the Loop approach has been used to bring the obtained results as close as possible to reality and with a minimum of constraints. Based on the analysis of the obtained results, some experimental parameters are summarized and a comparison table is synthesized.